Hello!
Not sure if this is the best place to post but here we go:
I would like to know how I would go about putting a semi-truck horn working on vacuum onot a bicycle. I have seen some YouTube videos, but I do not really get how the horn really works and how I would go about putting it on a 12V battery?
I found this horn from hongkong and was wondering if this pack will need anything extra to setup to a 12V battery, screenshot provided.
One last thing, I found this video with a horn on a bike and there was a switch that made the horn go in like a up and down tone, like they have one busses on dangerous roads etc. Could som1 tell me how I would get that sound? The video link is here (sorry cant post link yet) so please just search truck horn on bike, it will be the first video. Exact name of video is: Truck Horn on Bike - extrem loud!!! Video by king10993
Dont have much experience in this sort of thing yet, dont think I know much of the elctrical language use either, much help would be very much appriciated! Thank You for reading :)!
PS: again sorry I was not ebale to post link 
Hope it wont do much extra work!